Hardly topical or necessary at the moment, but it might be interesting for some. I put these in ten years ago for an outlay of about £50. They are only suitable for small lawns as they work on mains pressure. I bought the heads on eBay for £7 each and a reel of speed-fit water pipe and the fittings from a plumber's wholesaler. I put them in during an afternoon, Anyone could do the same. This was the "dry run" or should I say "wet run" to make sure it worked. The supply has to be equidistant from the two heads to balance the pressure. I cut six inch wedges out of the lawn, laid the pipe and replaced them. The scars disappeared after a couple of weeks. I had a water valve from the previous central heating system and some sand and cement in the garage to remake the path after I connected it up. A length of 1.5" polypipe protects the speed-fit from the ground up to the valve, in case I hit it with a wheelbarrow or whatever. All done and working. As it's plastic pipe it's not affected by frost. It's worked with no bother since 2010, though not used that often. The heads are adjustable, you can have a segment of part of the circle that stays dry as many degrees as you like. So I cut out 45 degrees of the bottom one so it doesn't water the teahouse. A smaller cut out in the top one stops it watering me when I turn it on or off. The borders are watered by a leaky hose. With hoselock valves either side of the rockery, the border from the house down to the bottom of the garden and round to the tea-house is therefore in three sections, so I can water all three or any combination of one or two sections. It has its own dedicated tap below the kitchen window. The supply runs under the patio and comes up behind what was once the waterfall at the end of the rockery.